From DE 10 2004 002 076 A1, a vane pump with a pump housing is known and a cam ring is mounted in the pump housing. In the cam ring, a rotor is arranged so that it can rotate about a rotational axis and the cam ring has an inner contour, with vane elements mounted on the rotor sliding against this inner contour when the rotor rotates about the rotational axis. In this way, lift sections with several pump chambers are formed for each lift section, with these chambers being limited by the vane elements in the circumferential direction.
The cam ring is mounted so that it can move in the pump housing and so that the cam ring can be moved out from a concentric arrangement with the rotor, wherein a lift section with a variable volume can be created and if the rotor is set in rotation with the vane elements, then the volume of each lift section that is divided in the circumferential direction by the vane elements for forming individual pump chambers increases and decreases. By increasing and decreasing the volumes of the pump chambers, a fluid can be suctioned from a suction opening that can be connected to a suction connection and the fluid can be fed to a pressure opening after compression through corresponding reduction of the pump chambers by means of a rotational angle of the rotor, so that the fluid can escape again compressed through the pressure opening from the pump chambers. Despite the displacement of the cam ring from the rotational axis, the inner contour of the cam ring here corresponds to a circle.
GB 848,760 A shows a vane pump with several lift sections that extend between an inner contour of a cam ring and a rotor. The inner contour of the cam ring has several indentations that include a contour like a cylindrical section. Distributed over the circumference, six lift sections are created in this way that are covered by the ends of the spring-loaded vane elements.
DE 43 03 115 A1 shows another embodiment of a vane pump with a cam ring in which a rotor is mounted so that it can rotate about a rotational axis and the inner contour of the cam ring has an elliptical shape. The outer ends of the vane elements slide on the inner contour. These ends are mounted on and rotate with the rotor and it is clear that, through the construction of the elliptical shape for forming the outer limits of the lift sections, larger pump chamber volumes can be created than with lift sections that are formed with an inner contour of a cam ring and have a cylindrical shape.
An elliptical contour disadvantageously leads to greater wear of the vane pump, which must be accounted for by using larger volumes for the pump chambers. If cylindrical inner contours of the cam ring are used to form the lift sections, for slightly less wear, only comparatively small volumes of the pump chambers are created, so that it is desirable to increase the volumes of the pump chambers without here increasing the wear of the vane pump.
The greater the radial height of the lift sections above the outer contour of the rotor is, the greater the vane elements accelerate outward and inward again in their lifting motion due to the sliding against the more strongly formed inner contour, as is created, for example, with an elliptical shape. In addition to increased wear, this acceleration behavior also leads to increased noise development, so that it is further desirable to optimize the acceleration profile of the vane cells when sliding against the inner contour for a minimal noise development.